Preheat oven to 275F and butter and flour your spring form pan.
Gently melt the butter and chopped chocolate together in a medium bowl. I do this in the microwave, starting with 30 seconds and adding another 15 seconds as needed, stirring in between to allow the heat of the bowl to fully melt everything. You can do this over a double boiler if you feel more comfortable that way. Set aside and let cool a bit.
When your chocolate mixture has cooled off a bit, whisk in the egg yolks and set aside. Note: if you try to whisk your eggs into very hot chocolate they will start to cook, not what we want!
Add your egg whites to the bowl of a stand mixer. You can also use electric beaters if you prefer. Whip them to foamy soft peaks, and then gradually add the sugar, while whipping. Continue whipping until you get firm glossy peaks.
Take about 1/4 of the egg whites and stir them into your chocolate mixture. Then transfer that into the bowl of egg whites. Carefully fold the two together until no streaks of egg whites remain. Do this gently so as not to deflate the whites.
Turn the batter into your prepared pan, smoothing out the top with an offset spatula.
Bake for 45-50 minutes, or until risen and no longer wobbly in the center. The sides of the cake will just be beginning to pull away from the pan.
Let cool for about 10-15 minutes, and then run a knife around the edges to loosen any stuck bits before removing the sides of your pan.
When the cake has cooled, dust with powdered sugar before serving. Leftovers can be stored under a cake dome or loosely covered with foil at room temperature. It can also be refrigerated.
Notes
*Be careful when separating eggs ~ you don't want any of the yolk to get into the whites, or they won't whip up as well.Recipe from Martha Stewart
Nutritional information is provided as a courtesy and is an estimate only. This information comes from online calculators. Although The View from Great Island attempts to provide accurate nutritional information, these figures are only estimates.
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